2006 National Ambient Air Quality Standards (NAAQS) for Particulate Matter (PM2.5)
In 2006, based on the EPA’s review of the air quality criteria and national ambient air quality standards (NAAQS) for particulate matter (PM), EPA made revisions to the primary and secondary NAAQS for PM.
With regard to primary standards for fine particles (generally referring to particles less than or equal to 2.5 micrometers (μm) in diameter, PM2.5), EPA revised the level of the 24-hour PM2.5 standard to 35 micrograms per cubic meter (μg/m3) and retained the level of the annual PM2.5 standard at 15μg/m3.
With regard to primary standards for particles generally less than or equal to 10μm in diameter (PM10), EPA retained the 24-hour PM10 and revoked the annual PM10 standard. With regard to secondary PM standards, EPA made them identical in all respects to the primary PM standards, as revised.
10/17/2006 – Final Rule
01/17/2006 – Proposed Rule